Consolidated Statements of Stockholders' Equity - Parenthetical - $ / shares	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 1.36	$ 1.20	$ 1.00